(3)[P] Investigating Enzymatic Reactions

What is amalyse

A digestive enzyme that breaks down starch

How can starch be detected in a solution

Iodine solution

What colour will iodine be if no starch is present

Brown

What colour will iodine solution be if starch is present

Blue-black

Step 1 of Practical

Put a drop of iodine solution into every well of a spotting tile

Step 2 of practical

• Place a bunsen burner on top ofo a heatproof mat, and a tripod and gauze over the bunsen burner

• Place a beaker of water on top and heat till 35 degrees celsius

Step 3 of practical

Add 1cm³ of amalyse solution and 1cm³ of buffer solution with a pH of 5 in a boiling tube. Put the tube into the beaker of water for 5 minutes.

Step 4 of practical

Use a new syringe to add 5 cm³ of starch solution to the boiling tube

Step 5 of practical

Mix the contents and start a stop-clock

Step 6 of practical

Every 30 seconds, use a pipette to take a sample of the boiling tube and put it in a well in the spotting tile

Step 7 of the practical

Repeat the experiment with different pH values

What is the dependent variable

Time taken for starch to be broken down

What is the independent variable

pH of buffer solution

Name a control variable

• Temperature of water

• Amount of starch

• Amount of amalyse solution

How to calculate rate of reaction?

rate\left(s^{-1}\right)=\frac{1000}{time\left(\sec onds\right)}